A ray of light passes through an equilateral glass prism in such a manner that the angle of incidence is equal to the angle of emergence and each of these angles is equal to `3//4` of the angle of the prism. The angle of deviation is

Options

A. `45^(@)`
B. `39^(@)`
C. `20^(@)`
D. `30^(@)`

Answer

D

Explanation

Given `i=e=(3)/(4)A=(3)/(4)xx60=45^(@)`
In the position of minimum deviation
`2i=A+delta_(m)` or` delta_(m)=2i-A=90-60=30^(@)`